Nash Professor of Law at Columbia University. Corresponding member, The British Academy; Titular Member, International Academy of Comparative Law; honorary Vice President, American Society of International Law; honorary editor of the American Journal of International Law and of the Slavic Review. Previously Professor of Public Law and Member of the Russian Institute, Columbia University. President, American branch, International Law Assn. 1973-75; President, American Foreign Law Assn. 1973-75.